Exam Review

• Virtual Machine
  • hides complexity and limitations of hardware from application programmers
• Hiding Complexity
  • advantages: simpler, no physical worries
  • disadvantages: lack of control, false assumptions about black box
• General OS Functions
  • screen display
  • storage accesses
  • coordination amond applications
• Coordination
  • applications should not crash one another
  • address space: memory addresses that an application can touch
  • an application should not crash OS
• Operating System
  • overcomes hardware
  • protects from one another
  • allocates resources
• Batch System
  • collects a batch of jobs before processing
• Multiprocessing
  • multiple programs can run concurrently
• Timeshare systems
  • each user can afford to own terminals and interact with machines
• Multitasking
  • a single user can run multiple programs on the same machine at the same time
  • Multiprocessing